Expansible endoprosthesis for a human or animal tubular organ, and fitting tool for use thereof

ABSTRACT

An endoprosthesis includes an extensible tubular mesh embedded in a plastic or elastomer extensible film. A tool for positioning the endoprosthesis includes a tube-shaped guide provided at its distal end with a tulip-shaped housing. Cutting threads cause the housing to open longitudinally into several petal-like parts. Application is to endoluminal treatment of aneurisms and dilations.

BACKGROUND OF THE INVENTION

The present invention relates to an expansible endoprosthesis for ahuman or animal tubular organ, of the type comprising an expansible meshof cylindrical general shape, and is useful in particular for theendoluminal treatment of aneurisms and to dilations.

Endoprostheses of this type generally consist of a single metal meshwhich can be expanded using a balloon, or are auto-expansible, i.e.self-expanding. After a transluminal dilation, they are insertedendoluminally using a probe, then expanded or released.

These known endoprostheses are not entirely satisfactory, because thetissues penetrate the cavities of the mesh and are traumatized and, inaddition, the endoprosthesis creates turbulence in the blood flow.

Furthermore, these endoprostheses cannot be used for treating aneurisms,or more generally for connecting two healthy segments of a tubular organsuch as a vessel, since they are not liquid-tight.

SUMMARY OF THE INVENTION

The object of the invention is to provide an expansible endoprosthesiswhich eliminates these draw-backs. For this purpose, the inventionprovides an endoprosthesis of the aforementioned type, but wherein amesh is embedded in an extensible and biocompatible plastic or elastomerfilm, this film filling the cavities of the mesh and covering the entiresurface of the mesh substantially throughout the whole extent of theendoprosthesis.

According to other characteristics:

the film consists of a polymer such as polyurethane or a natural orsynthetic rubber;

the endoprosthesis is of the auto-expansible or self-expanding type, andthe end parts of the endoprosthesis are flared when it is in itsexpanded state;

the mesh is made of stainless steel or of a relatively rigid plasticsuch as polytetrafluoroethylene which has been made radiopaque.

Another aspect of the invention is a tool for fitting an auto-expansibleendoprosthesis as defined above. This tool comprises:

a guide tube provided at its distal end with a tulip-shaped part forhousing the endoprosthesis in the contracted state; and

means for opening the tulip-shaped part longitudinally.

According to one embodiment, such means comprise wires for cutting thetulip-shaped part into several petal-like parts, such wires beingconnected to an actuation handle.

According to another embodiment, such means comprise a longitudinalopening of the tulip-shaped part, each edge of which has a series ofgussets, the gussets of the two edges being fitted into each other andbeing held by a cord which passes through them and which is connected toan actuation handle.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to theattached drawings, in which:

FIG. 1 diagrammatically represents an endoprosthesis according to theinvention in a retracted state;

FIG. 2 diagrammatically represents the same endoprosthesis in anexpanded state;

FIG. 3 represents, on a greatly enlarged scale, in perspective, a toolfor fitting an auto-expansible endoprosthesis according to theinvention;

FIG. 4 is a view in longitudinal section of the tool in FIG. 3;

FIG. 5 is a view taken in section along the line V--V in FIG. 4;

FIG. 6 illustrates the use of the tool in FIGS. 3 to 5;

FIG. 7 represents the corresponding expansion of the endoprosthesis;

FIG. 7A shows flaring of end portions; and

FIG. 8 diagrammatically represents, on a greatly enlarged scale and inperspective, another tool for fitting an auto-expansible endoprosthesisaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The endoprosthesis 1 represented in FIGS. 1 and 2 consists of a tubularmesh 2 embedded in a film 3.

The mesh consists of stainless steel of biocompatible grade. Mesh 2 canbe made by weaving or knitting of a yarn, axial spreading of a tube, orby any other suitable technique. It is plastically deformable, that isto say that it has a first stable shape of small diameter, representedin FIG. 1, in which the cavities form diamonds elongated parallel to itsaxis, and a second stable shape of greatly enlarged diameter and shorterlength, represented in FIG. 2, in which the cavities form diamondselongated in the circumferential direction. Mesh 2 has an axis X (FIG.2), opposite ends or end portions and a body or main portion extendingbetween said end portions, as clearly illustrated. The material of mesh2 has an exposed surface including (with reference to FIG. 7A forpurposes of clarity of illustration) portions 2a facing radiallyinwardly with respect to axis X, portions 2b facing radially outwardlywith respect to axis X, and portions 2c facing toward and defining eachof the cavities.

The mesh 2 is entirely embedded in film 3 of an extensible andliquid-tight material which fills its cavities. Film 3 covers and isattached to the entire exposed surface of mesh 2 including portions 2athereof defining the cavities therein. The extensibility of thismaterial is sufficient for the film 3 to be able to follow thedeformation of the mesh 2 from its contracted state to its expandedstate without tearing or detachment, despite the deformation of thecavities of the mesh. Appropriate materials are a biocompatibleelastomer, which may be a natural or synthetic rubber, or alternativelya biocompatible polymer such as polyurethane.

The coating of the mesh 2 with the film 3 may be carried out bytechniques of co-extrusion or immersion, after degreasing of the metaland its treatment with a primary adhesion substance.

In the expanded state (FIG. 2), a liquid-tight tubular segment is thenobtained which can be used as an endoprosthesis or "stent" after atransluminal dilation. This endoprosthesis does not traumatize thetissues and creates practically no turbulence in the blood flow, sincethe tissues and the blood are in contact with a practically smoothelastomer or polymer surface.

Because of its leaktightness, the endoprosthesis can be used forendoluminal treatment of an aneurism, by making it bridge the aneurism,each of its ends being applied radially against the inner wall of ahealthy artery segment adjacent to the aneurism.

In another embodiment, illustrated in FIGS. 3 to 7, the mesh 2 of theendoprosthesis 1A is auto-expansible, which is obtained conventionallyby using stainless steel with spring properties.

For fitting the endoprosthesis 1A, it is compressed radially into itsconfiguration in FIG. 1, which is not stable, and it is inserted into atulip-shaped end 4 of a tool 5 represented in FIGS. 3 to 5.

The distal end of the tulip-shaped part 4 is open and has three notches6 spaced at angles of 120° from each other. Its proximal end forms aninner shoulder 7 from which extends a guide tube 8. In the plane of eachnotch 6, a channel 9 formed in the thickness of the wall of the tube 8emerges outwards through radial orifices 10, 11, on the one hand nearthe shoulder 7, and on the other hand near the proximal end of the tube8.

It is also possible to provide in the thickness of the wall of the tube8, as shown, longitudinal channels 12, 13 for injecting fluids, whichchannels start from the proximal end of tube 8 and emerge into a spaceinwardly of the tube 8 near the shoulder 7.

In each of the three aforementioned planes, a flexible wire 14 passesthrough the respective notch 6. An inner strand 15 of wire 14 runs alongthe inner wall of the tulip-shaped part 4, passes through an orifice 16provided in the shoulder 7, penetrates the orifice 10, extends along thechannel 9, leaves through the orifice 11 and rejoins an actuation handle17 (FIG. 3). An outer strand 18 of the wire 14 runs along the outer wallof the tulip-shaped part, follows the same path 10, 9, 11 as the strand15, and also rejoins the handle 17. Handle 17 is therefore connected tosix wire strands, and the three inner strands 15 are pressed flatagainst the inner wall of the tulip-shaped part by the tendency of theendoprosthesis 1A to expand.

Before using the endoprosthesis, after a transluminal dilation or fortreating an aneurism, the tool 5 is threaded onto a guide, insertedthrough the skin and conveyed endoluminally as far as the desiredlocation.

The operator then pulls on the handle 17. This tensions the three wires15, and these wires each cut the tulip-shaped part 4 along onegeneratrix. The tulip-shaped part then progressively releases theendoprosthesis, which expands by itself, as illustrated in FIG. 6. Whenthe tulip-shaped part is completely open, the tool is withdrawn bypulling on the tube 8.

In the expanded state (FIG. 7A), it is seen that the two ends of theendoprosthesis are automatically flared, which provides two advantageouseffects: on the one hand, the leaktightness of the endoprosthesis andthe artery is reinforced, and, on the other hand, the ends 29 of thewires of the mesh 2 extend slightly beyond the film 3 and form as manypoints for anchoring the endoprosthesis in the artery. Theendoprosthesis is thus positionally stabilized.

Other materials may be used to form the mesh 2. For example, in order toproduce an auto-expansible endoprosthesis, a yarn of a relatively rigidpolymer with spring properties, such as polytetrafluoroethylene (PTFE),which has been made radiopaque, may be used.

Another embodiment of the tool 5 has been represented diagrammaticallyin FIG. 8. This tool differs from that described hereinabove by themeans for longitudinal opening of the tulip-shaped part.

The tulip-shaped part is actually slit longitudinally over its entireheight. Each edge of the slot includes a series of projectingcylindrical gussets 20. When the tulip-shaped part is in its closedcylindrical state, and holds an auto-expansible endoprosthesis 1A in thecontracted state, the gussets 20 of the two edges interpenetrate, andthe whole is held by a cord 21 which passes through all the gussets andis connected, at its proximal end, to the actuation handle 17.

The endoprosthesis is released simply by pulling on the handle 17.

We claim:
 1. A self-expanding stent comprising:a generally tubularself-expanding mesh formed of a material having spring properties, saidmesh having an axis, opposite ends and a body portion extending axiallybetween said ends, said mesh defining therethrough a plurality ofopenings, and said material of said mesh having an exposed surfaceincluding portions facing radially outwardly and radially inwardly withrespect to said axis and portions facing toward each of said openings,said mesh being deformably expansible from a contracted state to anexpanded state; a liquid-tight film formed of an extensible andbiocompatible material; at least said body portion of said mesh beingentirely embedded within said film, such that said film fills andbridges said openings of said body portion of said mesh, and with saidfilm covering and being attached to the entire said exposed surface ofsaid body portion of said mesh; and said material of said film having anextensibility sufficient to enable said film to follow and move withsaid mesh during deformation thereof from said contracted state to saidexpanded state.
 2. A stent as claimed in claim 1, wherein said filmmaterial is a polymer.
 3. A stent as claimed in claim 1, wherein saidfilm material is polyurethane.
 4. A stent as claimed in claim 1, whereinsaid film material is natural rubber.
 5. A stent as claimed in claim 1,wherein said film material is synthetic rubber.
 6. A stent as claimed inclaim 1, wherein end portions of said stent are flared when said stentis in an expanded condition thereof.
 7. A stent as claimed in claim 1,wherein said mesh material comprises stainless steel.
 8. A stent asclaimed in claim 1, wherein said mesh material comprises a rigidplastic.
 9. A stent as claimed in claim 8, wherein said rigid plasticmesh material comprises polytetrafluoroethylene.
 10. A stent as claimedin claim 8, wherein said rigid plastic mesh material is radiopaque. 11.A stent as claimed in claim 1, wherein said film is a plastic material.12. A stent as claimed in claim 1, wherein said film is an elastomermaterial.
 13. A stent as claimed in claim 1, wherein said openings ofsaid mesh are diamond-shaped and are elongated parallel to said axis ofsaid mesh in said contracted state of said mesh and are elongatedcircumferentially of said mesh in said expanded state of said mesh. 14.A stent as claimed in claim 1, wherein said extensibility of saidmaterial of said film is sufficient to prevent said film from tearingaway or detaching from said mesh during said deformation.
 15. A stent asclaimed in claim 1, wherein said film comprises a unitary one-piecestructure.
 16. An expansible stent comprising:a generally tubular meshhaving an axis, opposite ends and a body portion extending axiallybetween said ends, said mesh defining therethrough a plurality ofopenings, and said mesh having an exposed surface including portionsfacing radially outwardly and radially inwardly with respect to saidaxis and portions facing toward each of said openings, said mesh beingdeformably expansible from a contracted state to an expanded state; aliquid-tight film formed of an extensible and biocompatible material; atleast said body portion of said mesh being entirely embedded within saidfilm, such that said film fills and bridges said openings of said bodyportion of said mesh, and with said film covering and being attached tothe entire said exposed surface of said body portion of said mesh; andsaid material of said film having an extensibility sufficient to enablesaid film to follow and move with said mesh during deformation thereoffrom said contracted state to said expanded state.
 17. A stent asclaimed in claim 16, wherein said film material is a polymer.
 18. Astent as claimed in claim 16, wherein said film material ispolyurethane.
 19. A stent as claimed in claim 16, wherein said filmmaterial is natural rubber.
 20. A stent as claimed in claim 16, whereinsaid film material is synthetic rubber.
 21. A stent as claimed in claim16, wherein end portions of said stent are flared when said stent is inan expanded condition thereof.
 22. A stent as claimed in claim 16,wherein said mesh is formed of stainless steel.
 23. A stent as claimedin claim 16, wherein said mesh is formed of a rigid plastic.
 24. A stentas claimed in claim 23, wherein said rigid plastic comprisespolytetrafluoroethylene.
 25. A stent as claimed in claim 23, whereinsaid rigid plastic is radiopaque.
 26. A stent as claimed in claim 16,wherein said film is a plastic material.
 27. A stent as claimed in claim16, wherein said film is an elastomer material.
 28. A stent as claimedin claim 16, wherein said openings of said mesh are diamond-shaped andare elongated parallel to said axis of said mesh in said contractedstate of said mesh and are elongated circumferentially of said mesh insaid expanded state of said mesh.
 29. A stent as claimed in claim 16,wherein said extensibility of said material of said film is sufficientto prevent said film from tearing away or detaching from said meshduring said deformation.
 30. A stent as claimed in claim 16, whereinsaid film comprises a unitary one-piece structure.